THE FKESH-WATER SPONGE. 
139 
animaux and which Lieberkiihn, thirty years afterwards, calls 
by the awkward appellation of swarm-spores,” and describes as 
swimming actively about in the vessel of water in which they 
were placed. 
My own account of the locomotive gemmules in 1838 was as 
follows : — They are minute, though some are less than others, 
and are plainly visible to the naked eye ; they are white, of a 
somewhat globular or rather more oval shape, the lower or 
smaller portion being opaque, and the upper transparent and 
membranous. Their movements in swimming were no less 
astonishing than elegant ; ascending from the sponge at the 
bottom of the water to the surface, floating gently on the sur- 
face, or traversing the middle of the fluid like a balloon in the 
air, or suspending themselves nearly in one spot, or whirling 
round and round, describing larger or smaller circles in the 
water, approaching or avoiding each other; but, when perform- 
ing their quicker progressions, they move along on their sides 
with their rounder ends precedent. I put several of these 
germ-like bodies into a wine-glass full of spring- water, adding 
fresh daily to them ; after a day or two their gyratory motions 
became weaker and slower, and at length they entirely ceased 
then the bodies attaching themselves to the bottom and sides of 
the glass, and losing their original shape, became flatter, the 
transparent membranes of their upper portion disappearing, the 
white opaque portions alone were left, which, resembling minute 
specks, at the expiration of a few more days increased to such 
a sufficient size as to show, with the aid of a magnifier, that 
they are undoubtedly the rudiments of the Spongilla itself, and 
thus proving That they are its reproductive bodies or sporules.” 
The sann; glass, with the germinating specks or gemmules 
attached to it, was exhibited to the Linnaean Society in the 
same year. I could not determine whether these locomotive 
gemmules became identical with the fixed seed-like bodies, or 
whether the former are the real sporules, and the latter the 
sporidia. Mr. Carter states, that the locomotive corpuscules are 
impelled by cilia in their movements, and that they are merely 
ciliated forms of the seed-like bodies. 
This question is still undecided ; as also is that more difficult' 
one. How do the very minute cilia put into rapid motion these 
gemmules, since no muscular apparatus has been detected in 
them, as it has in the like moving germs, or gemmules, of the 
Zoophytes ? 
Professor Williamson’s plate does not give any representation 
of the smaller white locomotive gemmules, which are so elegant 
in their excentric movements. Fig. 13, one of the granules 
from the interior of the seed-like bodies (figs. 7 and 12), is dif- 
YOL. VII. NO. XXVII. ' L 
